Hydrogen Sulfide

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Evaluate Exposure

Identify processes that could release or produce hydrogen sulfide. This includes identifying known sources of hydrogen sulfide and evaluating possible fire and explosion hazards. Use a Process or Job Hazard Analysis for identifying and controlling hazards.

Test (monitor) the air for hydrogen sulfide. This must be done by a qualified person. Use the right test equipment, such as an electronic meter that detects hydrogen sulfide gas.

Conduct air monitoring prior to and at regular times during any work activity where hydrogen sulfide exposure is possible. When working in confined spaces air monitoring must be conducted in accord with the applicable OSHA standards. Detector tubes, direct reading gas monitors, alarm only gas monitors, and explosion meters are examples of monitoring equipment that may be used to test permit space atmospheres.

NIOSH Method 6013. Air samples are collected with a glass tube and personal sampling pump and analyzed with ion chromatography.

DO NOT rely on your sense of smellto indicate the continuing presence of hydrogen sulfide or to warn of harmful levels. You can smell the "rotten egg" odor of hydrogen sulfide at low concentrations in air. But after a while, you lose the ability to smell the gas even though it is still present (olfactory fatigue). This loss of smell can happen very rapidly and at high concentrations and the ability to smell the gas can be lost instantly (olfactory paralysis).

Control Exposures

Use exhaust and ventilation systems to reduce hydrogen sulfide levels. Make sure that the system is:

Non-sparking

Grounded

Corrosion-resistant

Separate from other exhaust ventilation systems

Explosion-proof

These safety measures are important because hydrogen sulfide is flammable and can corrode materials if they are not properly protected. When working in confined spaces ventilation should operate continuously and must be conducted in accord with the applicable OSHA standards.

Train and educate workers about hazards and controls. Training topics may include:

WARNING: First responders must be trained and properly protected before entering areas with elevated levels of hydrogen sulfide.

Rescuer protection should include:

Positive-pressure, self-contained breathing apparatus (SCBA).

A safety line to allow for rapid exit if conditions become dangerous.

Use respiratory and other personal protective equipment. If engineering and administrative controls cannot reduce hydrogen sulfide below OSHA's permissible exposure limit, employers must provide respiratory protection and other personal protective equipment (PPE), such as eye protection and possibly fire-resistant clothing. Employers must complete a PPE hazard assessment and equipment selection process in accord with the OSHA regulations before beginning any work activities. Respiratory protection should be at least:

For exposures below 100 ppm, use an air-purifying respirator with specialized canisters/cartridges for hydrogen sulfide. A full face respirator will provide eye protection.

For exposures at or above 100 ppm, use a full face pressure demand self-contained breathing apparatus (SCBA) with a minimum service life of thirty minutes or a combination full face pressure demand supplied-air respirator with an auxiliary self-contained air supply. Exposures at or above 100 ppm are considered immediately dangerous to life and health (IDLH).

Whenever respirators are used, the employer must have a respiratory protection program that meets the requirements of OSHA's Respiratory Protection standard (29 CFR 1910.134). This program must include proper respirator selection, fit testing, medical evaluations, and training. For more information on respiratory protection see:

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